Of course there are more than one person named John Mytton. It just isn't the real name of the member on this forum using that name, and he has admitted as much.
I love the phrase "admitted as much," as though this required an "admission."

Especially coming from someone who is doing the same thing!
Cross-examining attorney: "Do you ADMIT, Mr. Mytton, that you post on obscure internet forums using the name of a 19th Century British eccentric? Well, DO YOU OR DO YOU NOT ADMIT THIS? And yet you expect this jury to believe that you, who have ADMITTEDLY appropriated a noted historical figure's name for your own selfish purposes, are innocent of the heinous crimes with which you are charged? Ladies and gentlemen of the jury, the prosecution rests."
In my long posting history, I have been, at least, Pastor Lance, Runner, Irkle Berserkle, Little Bo Peep, The Venerable Bede, Troglodyte74, Bingo and probably 25 others. I have great fondness for my Venerable Bede persona, may he rest in peace.
Sock puppets? That's a different story. Most forums explicitly prohibit them because they are fundamentally dishonest and serve no purpose other than to deceive. But you already knew that - right, mate?
This thread is rapidly becoming my absolutely most-favorite-ever Monty Python skit, and I've been doing this internet forum thing for almost 30 years.